U.S. Pat. Nos. 6,586,141 and 6,673,497 issued to Efimov et al. on Jul. 1, 2003 and Jan. 6, 2004, respectively, teach how to make diffractive optical elements from photosensitivity photo-thermo-refractive (PTR) glass with efficiency exceeding 95% and use of such elements, which are implied as volume Bragg gratings produced by interference of collimated beams, for angular and spectral beam transformations. These elements are spatial filter, attenuator, beam splitter, beam sampler, beam deflector controlled by angular positioning of grating or spectral scanning of the incident beam, selector of particular wavelengths, also known as notch filter or add/drop element, spectral shape former, also known as gain equalizer, spectral sensor, also known as wavelocker or wavelength meter, angular sensor, also known as angular pointer, Bragg spectrometer, also known as spectral analyzer, and selectors of transverse and longitudinal modes in laser resonators. All these diffractive optical elements are based on the use of specific angular and spectral selectivity of Bragg gratings.
A known use for such gratings is described in Igor V. Ciapurin, Leonid B. Glebov, Vadim I. Smirnov, Modeling of phase volume diffractive gratings, part 1: transmitting sinusoidal uniform gratings, Optical Engineering 45 (2006) 015802, pp. 1-9 for modeling of spectral and angular selectivity of transmitting gratings. It was shown that spectral and angular selectivity of Bragg gratings could be controlled by proper selection of their basic parameters which are spatial frequency, refractive index modulation, and thickness. The range of variations of Bragg gratings parameters, spectral or angular selectivity, is very wide and covers almost all requirements of different optical and laser systems.
A prior art Universal Beam controller is described in P. F. McManamon and E. A. Watson, “Nonmechanical beam steering for passive sensors,” in Proc. SPIE 4369, (2001) pp. 140-148 and Paul F. McManamon, Jianru Shi, and Philip J. Bos. Broadband optical phased-array beam steering. Optical Engineering 44 (2005) 128004, pp. 1-5 which describes an approach based on the use of a sequence of optical phased array (OPAs) for zone selection, a stack of PTR Bragg gratings for zone pointing, and one more OPAs for zone filling. The device described is based on creation of a thin phase grating with variable period in an electrically controlled liquid crystal phased array. This OPA produces small angle deflection by changing a period of a thin grating by re-arrangement of voltage.
The closest prior art to the present invention is a Universal Beam controller described in Paul F. McManamon, Jianru Shi, and Philip J. Bos. Broadband optical phased-array beam steering. Optical Engineering 44 (2005) 128004, pp. 1-5 which uses a sequence of optical phased arrays for zone selection, a stack of PTR Bragg gratings for zone pointing, and one more optical phased arrays for zone filling. The device described is based on creation of a thin phase grating with variable period in an electrically controlled LC phased array. This optical phased array produces small angle deflection by changing a period of a thin grating by re-arrangement of voltage.